Hi,

>>Is this phenomenon normal?Is there any idea about this problem?

It's a known problem with tcmalloc (search on the ceph mailing).

starting osd with "TCMALLOC_MAX_TOTAL_THREAD_CACHE_BYTES=128M" environnement 
variable should help.


Another way, is to compile ceph with jemalloc instead tcmalloc (./configure 
--with-jemalloc ...)



----- Mail original -----
De: "YeYin" <ey...@qq.com>
À: "ceph-users" <ceph-users@lists.ceph.com>
Envoyé: Lundi 17 Août 2015 11:58:26
Objet: [ceph-users] tcmalloc use a lot of CPU

Hi, all, 
When I do performance test with rados bench, I found tcmalloc consumed a lot of 
CPU: 

Samples: 265K of event 'cycles', Event count (approx.): 104385445900 
+ 27.58% libtcmalloc.so.4.1.0 [.] tcmalloc::CentralFreeList::FetchFromSpans() 
+ 15.25% libtcmalloc.so.4.1.0 [.] 
tcmalloc::ThreadCache::ReleaseToCentralCache(tcmalloc::ThreadCache::FreeList*, 
unsigned long, 
+ 12.20% libtcmalloc.so.4.1.0 [.] 
tcmalloc::CentralFreeList::ReleaseToSpans(void*) 
+ 1.63% perf [.] append_chain 
+ 1.39% libtcmalloc.so.4.1.0 [.] 
tcmalloc::CentralFreeList::ReleaseListToSpans(void*) 
+ 1.02% libtcmalloc.so.4.1.0 [.] tcmalloc::CentralFreeList::RemoveRange(void**, 
void**, int) 
+ 0.85% libtcmalloc.so.4.1.0 [.] 0x0000000000017e6f 
+ 0.75% libtcmalloc.so.4.1.0 [.] 
tcmalloc::ThreadCache::IncreaseCacheLimitLocked() 
+ 0.67% libc-2.12.so [.] memcpy 
+ 0.53% libtcmalloc.so.4.1.0 [.] operator delete(void*) 

Ceph version: 
# ceph --version 
ceph version 0.87.2 (87a7cec9ab11c677de2ab23a7668a77d2f5b955e) 

Kernel version: 
3.10.83 

Is this phenomenon normal? Is there any idea about this problem? 

Thanks. 
Ye 


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